The proposed research program will focus on certain intrinsic functions of endothelium and smooth muscle which contribute to normal vascular homeostasis. Using established as well as newly developed techniques, homogeneous populations of each cell will be cultured from various types of blood vessels, arteries, veins, microvessels (human, bovine, rodent). The following features will be studied: endogenous prostaglandin production, and the effect of vasoactive substances or inflammatory mediators on this process; the presence of specific receptors for angiotensin II and prostaglandins, and factors controlling their regulation. Extension of the above studies to blood vessel cells from spontaneously hypertensive rats may help define pathogenetic mechanisms in altered vascular homeostasis.